Blood Flashcards
What initiates the intrinsic pathway of coagulation?
The subendothelial damage
What initiates the extrinsic pathway of coagulation?
The contact of blood to traumatized tissue
What is the intrinsic pathway cascade?
Factor 12 activates 11, then 11 activities 9 which activates 10 in the presence of 8
What is the extrinsic pathway cascade?
Traumatized tissues releases factor 3 which activates factor 7 and both of them together activates factor 10
What is the common pathway?
It starts with factor 10 being activated from the intrinsic or extrinsic pathway then factor 10 activates pro-thrombin to thrombin (factor2) which accordingly activates fibrinogen to fibrin (factor1)
What is hemophilia?
Deficiency of factor 8 mainly. It is x-linked disease. It might be acquired as an autoimmune disease but mostly appears in children.
What is the coagulation/bleeding profile in hemophilia?
⬆️APTT
Normal PT
Normal bleeding time
What is VWD (Avon Willbrand Disease)?
Deficiency of VW factor which is a glycoprotein that helps is platelet adhesion and serves as plasma carrier for factor 8.
It is diagnosed by desmopressin test, that assess the VWF antigen and activity. And treated by Cryoprecipitate (1,8,13,VWF)
What is the coagulation/bleeding profile in VWD?
⬆️APTT
⬆️Bleeding time
Normal PT
What are the most common hypercoagulability diseases?
Factor 5 Leiden
Anti-Phospholipid disease
Anti-Thrombin 3 deficiency
Protein C and S deficiency
What is Factor 5 Leiden?
It is the most common genetic disease that causes DVT &PE
What is anti-phospholipid disease?
The most common cause of DVT in pregnant woman with positive family history. Prolonged APTT
What are the antibodies present in antiphospholipid disease?
Anticardiolipin
Lupus anticoagulant antibody
What is the treatment of Anti-Thrombin 3 deficiency?
Warfarin for life
What is protein C and S?
These are proteins formed in the liver as vitamin K dependent factors (1972).
Thrombomodulin with thrombin forms a complex which activates protein C to active protein C which accordingly -in presence of protein S- inhibits factor 5 and 8.
So their deficiency cause hyper coagulability
What are parental anticoagulants?
LMWH (clexan) & unfractionated heparin
What are oral anticoagulants?
Warfarin (marivan)
How heparin works?
LMWH: ⬇️Factor 10 and doesn’t need follow up (but long half life)
Unfractionated heparin: binds with antithrombin 3 forming a complex that ⬇️ factors 2,9,10,11
The APTT must be 2-3 folds of normal
How does warfarin work?
It inhibits the vitamin K dependent factors 1972
Target PT is 2-3 folds of normal
When and how to stop the action of heparin?
If LMWH: 12-24 hours before surgery
If Unfractionated heparin: 4-6 hours before surgery
The antidote is protamine sulfate
What are the complications of heparin?
-Bleeding
-Heparin induced thrombocytopenia (HIT)
-Hyperkalemia (due to⬇️Aldosterone)
-Osteoporosis
When and how to stop the action of warfarin?
-It should be stopped 3-5 days before a surgery.
-If we need immediate reversal, then IV Vitamin K with PCC
If not rapid reversal then oral vitamin K
-IV Vit K works in 4 hours so that why PCC (Prothrombin complex concentrate) must be given with if as it works in 1 hour
-Oral Vit K works in 24 hours
-If PCC is not available, fresh frozen plasma might be given as an alternative with Vit K but with close monitoring (risk of overload)
How does the fibrinolytic system work?
The plasminogen is activated by the tissue plasminogen activator to plasminogen which dissolves fibrin threads
What is tranexamic acid (kepron)?
It inhibits the plasminogen to decrease or control bleeding
